1、 International Telecommunication Union ITU-T H.701TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU (03/2009) SERIES H: AUDIOVISUAL AND MULTIMEDIA SYSTEMSIPTV multimedia services and applications for IPTV General aspects Content delivery error recovery for IPTV services Recommendation ITU-T H.701 ITU-
2、T H-SERIES RECOMMENDATIONS AUDIOVISUAL AND MULTIMEDIA SYSTEMS CHARACTERISTICS OF VISUAL TELEPHONE SYSTEMS H.100H.199 INFRASTRUCTURE OF AUDIOVISUAL SERVICES General H.200H.219 Transmission multiplexing and synchronization H.220H.229 Systems aspects H.230H.239 Communication procedures H.240H.259 Codin
3、g of moving video H.260H.279 Related systems aspects H.280H.299 Systems and terminal equipment for audiovisual services H.300H.349 Directory services architecture for audiovisual and multimedia services H.350H.359 Quality of service architecture for audiovisual and multimedia services H.360H.369 Sup
4、plementary services for multimedia H.450H.499 MOBILITY AND COLLABORATION PROCEDURES Overview of Mobility and Collaboration, definitions, protocols and procedures H.500H.509 Mobility for H-Series multimedia systems and services H.510H.519 Mobile multimedia collaboration applications and services H.52
5、0H.529 Security for mobile multimedia systems and services H.530H.539 Security for mobile multimedia collaboration applications and services H.540H.549 Mobility interworking procedures H.550H.559 Mobile multimedia collaboration inter-working procedures H.560H.569 BROADBAND, TRIPLE-PLAY AND ADVANCED
6、MULTIMEDIA SERVICES Broadband multimedia services over VDSL H.610H.619 Advanced multimedia services and applications H.620H.629 IPTV MULTIMEDIA SERVICES AND APPLICATIONS FOR IPTV General aspects H.700H.719IPTV terminal devices H.720H.729 IPTV middleware H.730H.739 IPTV application event handling H.7
7、40H.749 IPTV metadata H.750H.759 IPTV multimedia application frameworks H.760H.769 IPTV service discovery up to consumption H.770H.779 For further details, please refer to the list of ITU-T Recommendations. Rec. ITU-T H.701 (03/2009) i Recommendation ITU-T H.701 Content delivery error recovery for I
8、PTV services Summary Recommendation ITU-T H.701 provides content delivery error recovery (CDER) mechanisms for IPTV services. It details the error recovery functions in the IPTV architecture and specifies detailed CDER mechanisms. It also provides guidelines on the applicability of the CDER mechanis
9、ms to different IPTV services and network conditions. Source Recommendation ITU-T H.701 was approved on 16 March 2009 by ITU-T Study Group 16 (2009-2012) under Recommendation ITU-T A.8 procedures. Keywords Content delivery error recovery, forward error correction, retransmission. ii Rec. ITU-T H.701
10、 (03/2009) FOREWORD The International Telecommunication Union (ITU) is the United Nations specialized agency in the field of telecommunications, information and communication technologies (ICTs). The ITU Telecommunication Standardization Sector (ITU-T) is a permanent organ of ITU. ITU-T is responsib
11、le for studying technical, operating and tariff questions and issuing Recommendations on them with a view to standardizing telecommunications on a worldwide basis. The World Telecommunication Standardization Assembly (WTSA), which meets every four years, establishes the topics for study by the ITU-T
12、 study groups which, in turn, produce Recommendations on these topics. The approval of ITU-T Recommendations is covered by the procedure laid down in WTSA Resolution 1. In some areas of information technology which fall within ITU-Ts purview, the necessary standards are prepared on a collaborative b
13、asis with ISO and IEC. NOTE In this Recommendation, the expression “Administration“ is used for conciseness to indicate both a telecommunication administration and a recognized operating agency. Compliance with this Recommendation is voluntary. However, the Recommendation may contain certain mandato
14、ry provisions (to ensure e.g., interoperability or applicability) and compliance with the Recommendation is achieved when all of these mandatory provisions are met. The words “shall“ or some other obligatory language such as “must“ and the negative equivalents are used to express requirements. The u
15、se of such words does not suggest that compliance with the Recommendation is required of any party. INTELLECTUAL PROPERTY RIGHTS ITU draws attention to the possibility that the practice or implementation of this Recommendation may involve the use of a claimed Intellectual Property Right. ITU takes n
16、o position concerning the evidence, validity or applicability of claimed Intellectual Property Rights, whether asserted by ITU members or others outside of the Recommendation development process. As of the date of approval of this Recommendation, ITU had received notice of intellectual property, pro
17、tected by patents, which may be required to implement this Recommendation. However, implementers are cautioned that this may not represent the latest information and are therefore strongly urged to consult the TSB patent database at http:/www.itu.int/ITU-T/ipr/. ITU 2010 All rights reserved. No part
18、 of this publication may be reproduced, by any means whatsoever, without the prior written permission of ITU. Rec. ITU-T H.701 (03/2009) iii CONTENTS Page 1 Scope 1 2 References. 1 3 Definitions 1 4 Abbreviations and acronyms 2 5 Conventions 3 6 Introduction 3 7 Content delivery error recovery archi
19、tecture 5 7.1 Content delivery error recovery in IPTV architecture 5 7.2 Content delivery error recovery functions 5 7.3 CDER interfaces and protocols 7 7.4 CDER control functional block 7 8 Content delivery error recovery mechanisms for streaming . 7 8.1 General . 7 8.2 Retransmission . 8 8.3 Forwa
20、rd error correction . 8 8.4 Hybrid combinations of FEC with retransmissions and feedback . 9 8.5 Usage guidelines for retransmission and FEC 10 9 Content delivery error recovery for content download services . 11 9.1 General . 11 9.2 Retransmission-based mechanism: reliable unicast download with TCP
21、 11 9.3 FEC-based mechanism: reliable multicast file distribution with FLUTE and FEC 12 9.4 Retransmission-based file repair procedures 12 Annex A FEC-based error recovery mechanisms for streaming distribution . 13 A.1 Assumptions . 13 A.2 Forward error correction according to ETSI TS 102 034 13 A.3
22、 Recommended FEC for linear TV services 15 A.4 Recommended FEC for content-on-demand services 16 Annex B Retransmission-based error recovery mechanisms for streaming delivery . 17 Annex C Content delivery error recovery for content download services 18 Appendix I Evaluation of CDER mechanisms for IP
23、TV services 19 I.1 Introduction 19 I.2 Evaluation criteria for multicast linear TV . 20 I.3 Evaluation criteria for content-on-demand services . 20 I.4 Evaluation criteria for content download services . 20 iv Rec. ITU-T H.701 (03/2009) Page Appendix II Use cases for content delivery error recovery
24、21 II.1 Linear TV service . 21 II.2 Tightly coupled content-on-demand service 23 II.3 Place-shifting service 25 Appendix III Evaluation results and recommended parameter settings for error recovery mechanisms 27 III.1 FEC according to ETSI TS 102 034 27 Bibliography. 30 Rec. ITU-T H.701 (03/2009) 1
25、Recommendation ITU-T H.701 Content delivery error recovery for IPTV services 1 Scope The ability to deliver high level of service quality to users is an essential aspect of IPTV services, and thus captured in many IPTV-related requirements. As IPTV services can easily be degraded if the media decode
26、rs are exposed to impairments such as packet losses, mechanisms are needed to reliably deliver good IPTV service quality in the presence of such defects. This Recommendation integrates error recovery in the IPTV architecture, describes specific mechanisms and discusses the applicability of the mecha
27、nism to IPTV services and network conditions, and provides recommendations and guidance on their use. 2 References The following ITU-T Recommendations and other references contain provisions which, through reference in this text, constitute provisions of this Recommendation. At the time of publicati
28、on, the editions indicated were valid. All Recommendations and other references are subject to revision; users of this Recommendation are therefore encouraged to investigate the possibility of applying the most recent edition of the Recommendations and other references listed below. A list of the cu
29、rrently valid ITU-T Recommendations is regularly published. The reference to a document within this Recommendation does not give it, as a stand-alone document, the status of a Recommendation. ITU-T Y.1541 Recommendation ITU-T Y.1541 (2006), Network performance objectives for IP-based services. ITU-T
30、 Y.1910 Recommendation ITU-T Y.1910 (2008), IPTV functional architecture. ITU-T Y.Sup5 ITU-T Y-series Recommendations Supplement 5 (2008), ITU-T Y.1900-series Supplement on IPTV service use cases. ARIB STD-B24 ARIB Standard, ARIB STD-B24, Data Coding and Transmission Specification for Digital Broadc
31、asting. ATIS-0800005 ATIS-0800005 (2006), IPTV Packet Loss Issue Report. ETSI TS 102 034 ETSI TS 102 034 v1.3.1 (2007), Digital Video Broadcasting (DVB); Transport of MPEG-2 TS Based DVB Services over IP Based Networks. SMPTE 2022-1 SMPTE specification 2022-1 (2007), Forward Error Correction for Rea
32、l-time Video/Audio Transport Over IP Networks. IETF RFC 793 IETF RFC 793 (1981), Transmission Control Protocol. IETF RFC 3550 IETF RFC 3550 (2003), RTP: A Transport Protocol for Real-Time Applications. IETF RFC 5052 IETF RFC 5052 (2007), Forward Error Correction (FEC) Building Block. IETF RFC 5053 I
33、ETF RFC 5053 (2007), Raptor Forward Error Correction Scheme for Object Delivery. 3 Definitions This Recommendation defines the following terms: 3.1 FEC base layer: Most important FEC layer. In the context of this Recommendation, this refers to the base layer in the FEC as specified in ETSI TS 102 03
34、4. 2 Rec. ITU-T H.701 (03/2009) 3.2 FEC enhancement layers: Subsequent FEC layers. In the context of this Recommendation, this refers to the enhancement layers in the FEC as specified in ETSI TS 102 034. 3.3 FEC layer: One FEC stream of multiple ordered FEC streams where support of this layer means
35、that all FEC streams with more important order are also supported. 3.4 FEC stream: IP packet stream associated with a media stream that contains redundant data to reconstruct a media stream locally at the IPTV terminal. 3.5 forward error correction (FEC): FEC-based CDER mechanisms generate redundant
36、 data to allow the IPTV terminal to correct packet losses. With this redundant information, the receivers can recover from packet losses locally at the IPTV terminal. 3.6 retransmission: Retransmission-based CDER mechanisms use feedback messages to recover from packet losses. 4 Abbreviations and acr
37、onyms This Recommendation uses the following abbreviations and acronyms: ALC Asynchronous Layered Coding AFEC Adaptive FEC ARQ Automatic Repeat Request ATIS-IIF Alliance for Telecommunication Industry Solutions IPTV Interoperability Forum AVP Audio-Visual Profile CBR Constant Bit Rate CDER Content D
38、elivery Error Recovery DSL Digital Subscriber Line DVB Digital Video Broadcasting ECG Electronic Content Guide EPG Electronic Program Guide FEC Forward Error Correction FLUTE File delivery over unidirectional transport FTP File Transfer Protocol ID Identifier IDR Instantaneous Decoder Refresh IP Int
39、ernet Protocol IPDV IP Packet Delay Variation IPER IP Packet Error Ratio IPLR IP Packet Loss Ratio IPTD IP Packet Transfer Delay IPTV IP Television MTBA Mean Time Between Artefacts NACK Negative ACKnowledgement QoE Quality of Experience Rec. ITU-T H.701 (03/2009) 3 QoS Quality of Service RMT Reliabl
40、e Multicast Transmission RTCP Real-Time Control Protocol RTP Real-Time Transport Protocol RTT Round-Trip Time SCP Service and Content Protection TCP Transmission Control Protocol TF Terminal Function TS Transport Stream TTS Timestamped Transport Stream UDP User Datagram Protocol VoD Video on Demand
41、XML eXtensible Markup Language 5 Conventions None. 6 Introduction Content delivery error recovery (CDER) is an important aspect for IPTV services. Data being delivered over IP networks may suffer from packet losses. In case of the delivery of video and audio, data errors, such as packet losses or bi
42、t errors being delivered to the media decoder, generally degrade the IPTV service quality. Moreover, losses in metadata such as electronic program guides (EPG), electronic content guides (ECG), and interactive user data may cause more severe problems in IPTV services. Therefore, data reliability sup
43、port is essential to IPTV services. This Recommendation addresses the requirement that the IPTV architecture provide a mechanism for resiliency of the service provider infrastructure in order to maintain a high QoE for video services ITU-T Y.Sup5. It addresses specific realizations of the content de
44、livery error recovery function and the content delivery error recovery client function in the IPTV architecture ITU-T Y.1910. Reference point E4 is used to exchange messages for delivering and requesting error recovery information ITU-T Y.1910. The support of content delivery error recovery mechanis
45、ms is not required for all networks, in particular for networks that can fulfil the desired IPTV service requirements. In case that a network cannot fulfil the packet loss requirements necessary to achieve the IPTV service requirements, the use of a content delivery error recovery solution is recomm
46、ended. Retransmission, forward error correction (FEC), and hybrid combinations of both are known mechanisms for error recovery. When an error recovery scheme and the associated protocol is selected, at least the following aspects should be taken into account: 1) type of IPTV service, e.g., linear TV
47、, content-on-demand, content download, EPG distribution, application data; 2) type of data delivery mechanisms, e.g., broadcast, multicast, unicast, overlay multicast, or peer-to-peer; 3) protocol or processing overhead at senders and receivers; 4) network bandwidth overhead aspects. 4 Rec. ITU-T H.
48、701 (03/2009) This Recommendation is structured as follows: Clause 7 introduces the content delivery error recovery architecture and provides some high-level descriptions of the involved functional blocks and interfaces. Clause 8 provides an overview on different CDER mechanisms for streaming, i.e.,
49、 for solutions in which the media stream is distributed in real-time and consumed at the same time. Clause 9 provides an overview on different CDER mechanisms for content download services, i.e., for solutions in which a media file is distributed to terminals for later consumption. This Recommendation also contains several annexes that contain specific recommendations for CDER mechanisms. The first release of this Recommendation is restricted to one annex specifying recommended FEC-b
